Bhagavad Gita 10.20

अहमात्मा गुडाकेश सर्वभूताशयस्थितः।अहमादिश्च मध्यं च भूतानामन्त एव च ॥१०.२०॥

ahamātmā guḍākeśa sarvabhūtāśayasthitaḥahamādiśca madhyaṃ ca bhūtānāmanta eva ca

I am the Self, O Gudakesa, seated in the hearts of all beings; I am the beginning, the middle, and the end of all beings.

गीता